Porting to GCC 6

[Ken Brown]

On 9/11/2017 7:48 PM, Yaakov Selkowitz wrote:
> Redirecting to cygwin-developers, as we don't have a patch yet.
> 
> On 2017-09-09 23:11, Brian Inglis wrote:
>> Getting failure building latest git with current gcc 6.3
> 
> There are more:
> 
> /home/Yaakov/src/cygwin/newlib-cygwin/winsup/cygwin/crt0.c: In function
> 'mainCRTStartup':
> /home/Yaakov/src/cygwin/newlib-cygwin/winsup/cygwin/crt0.c:23:3: error:
> calling '__builtin_return_address' with a nonzero argument is unsafe
> [-Werror=frame-address]
>     (void)__builtin_return_address(1);
>     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> make[3]: ***
> [/home/Yaakov/src/cygwin/newlib-cygwin/winsup/cygwin/../Makefile.common:44:
> crt0.o] Error 1
> /home/Yaakov/src/cygwin/newlib-cygwin/winsup/cygwin/init.cc: In function
> 'void threadfunc_fe(void*)':
> /home/Yaakov/src/cygwin/newlib-cygwin/winsup/cygwin/init.cc:26:36:
> error: calling 'void* __builtin_return_address(unsigned int)' with a
> nonzero argument is unsafe [-Werror=frame-address]
>     (void)__builtin_return_address(1);
>                                      ^
> make[3]: ***
> [/home/Yaakov/src/cygwin/newlib-cygwin/winsup/cygwin/../Makefile.common:41:
> init.o] Error 1
> /home/Yaakov/src/cygwin/newlib-cygwin/winsup/cygwin/fhandler_dsp.cc: In
> member function 'void
> fhandler_dev_dsp::Audio_out::buf_info(audio_buf_info*, int, int, int)':
> /home/Yaakov/src/cygwin/newlib-cygwin/winsup/cygwin/fhandler_dsp.cc:503:3:
> error: nonnull argument 'this' compared to NULL [-Werror=nonnull-compare]
>     if (this && dev_)
>     ^~
> /home/Yaakov/src/cygwin/newlib-cygwin/winsup/cygwin/fhandler_dsp.cc: In
> member function 'void
> fhandler_dev_dsp::Audio_in::buf_info(audio_buf_info*, int, int, int)':
> /home/Yaakov/src/cygwin/newlib-cygwin/winsup/cygwin/fhandler_dsp.cc:960:3:
> error: nonnull argument 'this' compared to NULL [-Werror=nonnull-compare]
>     if (this && dev_)
>     ^~
> /home/Yaakov/src/cygwin/newlib-cygwin/winsup/cygwin/pinfo.cc: In member
> function 'bool _pinfo::exists()':
> /home/Yaakov/src/cygwin/newlib-cygwin/winsup/cygwin/pinfo.cc:532:32:
> error: nonnull argument 'this' compared to NULL [-Werror=nonnull-compare]
>     return this && process_state && !(process_state & (PID_EXITED |
> PID_REAPED | PID_EXECED));
> 
> ~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> /home/Yaakov/src/cygwin/newlib-cygwin/winsup/cygwin/pinfo.cc: In member
> function 'commune_result _pinfo::commune_request(__uint32_t, ...)':
> /home/Yaakov/src/cygwin/newlib-cygwin/winsup/cygwin/pinfo.cc:723:3:
> error: nonnull argument 'this' compared to NULL [-Werror=nonnull-compare]
>     if (!this || !pid)
>     ^~
> /home/Yaakov/src/cygwin/newlib-cygwin/winsup/cygwin/pinfo.cc: In member
> function 'fhandler_pipe* _pinfo::pipe_fhandler(int64_t, size_t&)':
> /home/Yaakov/src/cygwin/newlib-cygwin/winsup/cygwin/pinfo.cc:822:3:
> error: nonnull argument 'this' compared to NULL [-Werror=nonnull-compare]
>     if (!this || !pid)
>     ^~
> /home/Yaakov/src/cygwin/newlib-cygwin/winsup/cygwin/pinfo.cc: In member
> function 'char* _pinfo::fd(int, size_t&)':
> /home/Yaakov/src/cygwin/newlib-cygwin/winsup/cygwin/pinfo.cc:835:3:
> error: nonnull argument 'this' compared to NULL [-Werror=nonnull-compare]
>     if (!this || !pid)
>     ^~
> /home/Yaakov/src/cygwin/newlib-cygwin/winsup/cygwin/pinfo.cc: In member
> function 'char* _pinfo::fds(size_t&)':
> /home/Yaakov/src/cygwin/newlib-cygwin/winsup/cygwin/pinfo.cc:859:3:
> error: nonnull argument 'this' compared to NULL [-Werror=nonnull-compare]
>     if (!this || !pid)
>     ^~
> /home/Yaakov/src/cygwin/newlib-cygwin/winsup/cygwin/pinfo.cc: In member
> function 'char* _pinfo::root(size_t&)':
> /home/Yaakov/src/cygwin/newlib-cygwin/winsup/cygwin/pinfo.cc:887:3:
> error: nonnull argument 'this' compared to NULL [-Werror=nonnull-compare]
>     if (!this || !pid)
>     ^~
> /home/Yaakov/src/cygwin/newlib-cygwin/winsup/cygwin/pinfo.cc: In member
> function 'char* _pinfo::cwd(size_t&)':
> /home/Yaakov/src/cygwin/newlib-cygwin/winsup/cygwin/pinfo.cc:933:3:
> error: nonnull argument 'this' compared to NULL [-Werror=nonnull-compare]
>     if (!this || !pid)
>     ^~
> /home/Yaakov/src/cygwin/newlib-cygwin/winsup/cygwin/pinfo.cc: In member
> function 'char* _pinfo::cmdline(size_t&)':
> /home/Yaakov/src/cygwin/newlib-cygwin/winsup/cygwin/pinfo.cc:979:3:
> error: nonnull argument 'this' compared to NULL [-Werror=nonnull-compare]
>     if (!this || !pid)
>     ^~
> /home/Yaakov/src/cygwin/newlib-cygwin/winsup/cygwin/pinfo.cc: In member
> function 'char* _pinfo::environ(size_t&)':
> /home/Yaakov/src/cygwin/newlib-cygwin/winsup/cygwin/pinfo.cc:1039:3:
> error: nonnull argument 'this' compared to NULL [-Werror=nonnull-compare]
>     if (!this || !pid)
>     ^~
> /home/Yaakov/src/cygwin/newlib-cygwin/winsup/cygwin/signal.cc: In member
> function 'int _pinfo::kill(siginfo_t&)':
> /home/Yaakov/src/cygwin/newlib-cygwin/winsup/cygwin/signal.cc:263:8:
> error: nonnull argument 'this' compared to NULL [-Werror=nonnull-compare]
>     else if (this && process_state == PID_EXITED)
>          ^~
> cc1plus: all warnings being treated as errors
> 
> Note that commit 0008bdea02b690ab19ffe997499cb9a96ee5a66d was intended
> to fix the nonnull-compare errors but had to be reverted.

I think I may have fixed this.  I found some errors in that commit. 
After fixing the errors, the zsh problem that caused the commit to be 
reverted was gone.  Of course there still could be some errors that I 
missed and that will show up later.

To simplify future debugging if there are further errors, I've broken 
the fix up into several commits that I'll send to cygwin-patches shortly.

Ken